If your company has a block of numbers (say 451-7661, 451-7662, etc.) it’s pretty easy to find one of these numbers and then figure out the sequence. Another thing that may have happened was somebody at your work (if it’s a large company) printed out a comprehensive phone list and has a buddy that he gave/sold it to.
At a company I used to work at this happened after the stock had gone up a bit and the company was in the news more. We had different financial advisers (no offense Rich) calling. At first we thought somebody sold the phone list, but after a few had cold called the CEO (which they probably wouldn’t have done if they had a list) we realized that they had just figured out our block of numbers.
Try to find out what company they are calling from and pass the info to your phone guys.
